The invention relates to an arrangement for filling air into a pneumatic tire arranged on a rim, rotating together with this rim and comprising a hose-type structure arranged essentially between the tire and the rim, which structure is connected at the end side with the environment and by way of a valve, with the interior of the tire and which, for filling the tire during its rotating movement, is locally squeezed from the environment side toward the tire interior. With respect to the technical background, reference is made to U.S. Pat. Nos. 5,052,456 and 4,922,984.
Normally, the pneumatic tires arranged on wheels of vehicles are filled, depending on the requirements, by way of a valve. An air lead-through provided in the pertaining wheel hub area is also known, which has controllable valves and a rotating air pump mounted in the wheel area, the driving torque of the air pump being generated during the wheel rotation by a mass with a center of gravity arranged in an offset manner. Furthermore, International Patent Document WO 02/051655 A2 discloses a device in the manner of an air pump which is driven by means of the self-movement of the tire bead during the rotating of the tire.
While a simple filling by way of the valve is readily neglected or forgotten, the filling by way of controllable valves requires high expenditures because of the required lines, the sensing of the wheel load and of the pressure as well as the pertaining control. Even the above-mentioned air pump constructions cause high constructional expenditures. In comparison, an arrangement according to the initially mentioned documents is simpler. In this case, a first embodiment illustrated in this document also still requires relatively high expenditures since, in this case, an independent contact pressure device is required by means of which a hose rotating together with the wheel or the tire is locally continuously squeezed, in which case this contact pressure device also should be capable of being positioned differently so that a filling of the tire is carried out only when required. In the case of a second embodiment illustrated in U.S. Pat. Nos. 5,052,456 and 4,922,984, no such contact pressure device is required. The pneumatic tire itself operates as such. However, according to this second embodiment, air can be pumped into tire only when the latter flat-spots considerably with its tire contact area; that is, now only has a very low internal pressure.
It is an object of the present invention to provide a simplified and nevertheless effective arrangement for filling a pneumatic tire.
According to the invention, a hose-type structure, which operates as an air pump as a result of locally displaced squeezing, is provided in the area of the so-called rim flange of the rim carrying the tire. When the geometrical design or the arrangement is suitable, it can be ensured in this area in a simple manner that a rotating tire with an internal pressure which is too low in the continuously moving-along contact area, (i.e., the circumferential section in each case representing the tire contact surface), continuously squeezes the hose-type structure such that, through this hose-type structure, as desired, air is conveyed or pumped into the tire interior from an intake section connected with the environment. Because of the tire deformation taking place when the interior tire pressure is too low, this takes place in the tire side wall area adjacent to the rim flange or in the bead chamfer bulge of the tire. In this case, a corresponding tire deformation occurs already when the internal tire pressure is only to a relatively small degree below the normal desired pressure value. If, in contrast, the internal tire pressure is in the range of the desired value or above, normally no correspondingly intensive tire deformation takes place, and—as desired—no additional air is then transported through the hose-type structure into the tire interior.
As far as the constructive design is concerned, the hose-type structure can be arranged in a duct, so that its position can be defined and maintained in a best possible manner. Thus, a duct can be provided in the rim flange, which duct at least partially receives the hose-type structure in the form of a hose. This hose is then squeezed while the wheel or tire rotates because of its contact area in a locally continuous manner by the section of the lateral tire wall close to the rim or by its so-called bead chamfer. As an alternative, a duct can be provided in the tire itself in the area of its bead chamfer, which duct at least partially receives the hose-type structure in the form of a hose. Then the squeezing force of the rotating rim flange is applied to the hose which, in the case of this arrangement, is also essentially pressed against the rim flange only in the respective contact section of the tire. Another embodiment of the present invention operates in a similar manner, in which a hollow duct is shaped in the tire itself in the area of its bead or bead chamfer, which hollow duct forms a hose-type structure and describes a closed cross-section. This hollow duct can be produced during the manufacturing of the tire, for example, by using the “non-permanent mold principle” from the casting practice or by the installation of a wire-shaped preform which can be pulled out after the heating process.
In principle, it is recommended that the geometry of the duct and of the hose-type structure or of the hollow duct forming the latter be selected such, and the additional elements participating in filling air into a tire by a local squeezing of the hose-type structure be designed such that this air-conveying squeezing takes place essentially only as long as the internal tire pressure is below a desired value required for the respective current wheel load. The process described above, in which, while the tire is rotating, the hose-type structure or the hose is locally squeezed having a displacing effect from the environment side toward the tire interior, will then take place only until the internal tire pressure has reached its desired value, after which, with a given load, the radial compression of the tire and thus the strength of the side wall or bead chamfer bulge is reduced to such an extent that the hose (or the hose-type structure) is no longer to the complete internal sealing and thus loses its air sealing capability; that is, can no longer pump or convey any additional air. Thus, when the components have a corresponding design, the overall system can therefore be virtually self-governing, according to the principle of a “high-pressure self-governed compressor”.
As mentioned above, by means of the hose-type structure, air can be conveyed from the environment into the tire interior by means of a locally displaced squeezing of the hose-type structure, in which case a suitable valve, particularly a check valve, is provided in the transition area to the tire interior. This check valve may be a flap valve or may be formed by the conventional tire valve. In addition, the hose-type structure may be equipped with a filter, particularly a hydrophobic capillary-pore membrane filter, on the intake side toward the environment. This prevents air contaminations present in the tire area and water from being brought into the tire air or into the hose-type structure, which may cause valve leakiness, clogging, icing and corrosion or chemical attacks there.